Brush holder assembly

ABSTRACT

A spring in a brush holder assembly is stressed both in torsion and in a cantilever manner for a dual purpose, the torsion stressing urging the brush in its brush holder aperture toward engagement with the commutator or slip ring and the cantilever stressing being available to act on one end of the spring adjacent a manual handle so that the handle may be moved along a cam wall increasingly stressing the spring in a cantilever direction until a detent notch is received whereat the spring is resiliently held in place and the torsion urging on the brush has been released. This permits an operator with one hand to release this spring urging on the brush and remove the brush from the dynamoelectric machine. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

United States Patent [72] Inventor Bernard T. l-ludak Athens, Ga. [21] Appl. No. 21,349 [22] Filed Mar. 20, 1970 [45] Patented June 29, 1971 [73] Assignee Reliance Electric Company [54] BRUSH HOLDER ASSEMBLY 14 Claims, 2 Drawing Figs.

[52] [1.8. CI. 310/246, 310/240, 310/247 [51] Int. Cl 110lr 39/40 [50] Field of Search 310/247, 246, 245, 242, 240, 239

[56] References Cited UNITED STATES PATENTS 1,730,913 10/1929 Brown .1 310/246 3,146,365 8/1964 Mi1ler..... 310/240X 2,691,114 10/1954 Lykins 310/246 Primary ExaminerMilton O. Hirshfield Assistant ExaminerB. A. Reynolds Att0rneyW00dling, Krost, Granger and Rust ABSTRACT: A spring in a brush holder assembly is stressed both in torsion and in a cantilever manner for a dual purpose, the torsion stressing urging the brush in its brush holder aperture toward engagement with the commutator or slip ring and the cantilever stressing being available to act on one end of the spring adjacent a manual handle so that the handle may be moved along a cam wall increasingly stressing the spring in a cantilever direction until a detent notch is received wheteat the spring is resiliently held in place and the torsion urging on the brush has been released. This permits an operator with one hand to release this spring urging on the brush and remove the brush from the dynamoelectric machine. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

PATENTEUJUMQIQH 3,590,298

INVENTOR. BEE/V420 7'. HUD/1K.

" WM, 77 M,

ATTOENE Y5.

BRUSH HOLDER ASSEMBLY BACKGROUND OF THE INVENTION On dynamoelectric machines such as motors and generators of the larger sizes wherein considerable amperage is passed through the brushes to the commutator or slip ring, the ease of servicing the brushes is an important consideration. It is customary in such brush holder assemblies to have a spring stressed to urge the brush toward the commutator or slip ring with this spring developing a fairly uniform force on the brush as the brush wears and despite the various positions of the outboard end of such brush. When the brush has worn sufficiently it must be replaced and such brush holder assemblies are generally in a crowdedlocation within an end bell or end frame of the dynamoelectric machine with access only through a small hole. It is difficult for an operator to put both hands into this space in order to change the brush and when he has both hands in such space, it is most difficult for him to see what he is doing.

Also the possibility of shock hazard is materially increased if an operator must put both hands inside this cramped space when changing the brush. This is because an electrical shock can travel from one hand to another through the heart giving rise to the possibility of electrocution.

It is not always 100 percent certain that the electric potential has been removed or will remain removed from the terminals of the machine and thus if an operator has two hands in this cramped space, the shock hazard is considerably increased.

Accordingly, an object of the invention is to provide a brush holder assembly which materially increases the facility with which the brush may be changed. I

Another object of the invention is to provide a brush holder assembly to permit changing the brush in a dynamoelectric machine with only one hand.

Another object of the invention is to provide a brush holder assembly with a spring which acts both as a torsion spring to urge the brush toward the commutator or slip ring and acts also as a cantilever spring for cooperation with detcnt means to retain this spring in inactive position relative to the brush.

SUMMARY OF THE INVENTION The invention may be incorporated in a brush holder assembly comprising, in combination, a body, a brush movably carried on said body for electrical engagement with a commutator or slip ring, a combined torsion and cantilever spring having first and second ends, detent means cooperating between said spring and said body, means mounting said spring for movement between first and second torsion spring positions with one of said positions acting between said body and said brush to urge said brush toward the commutator or slip ring, and means mounting said spring for movement between first and second cantilever spring positions with one of said positions being at said detent means and stressed as a cantilever spring and the other of said positions being spaced from said detent means, whereby an operator with one hand may move said spring from the first torsion and cantilever positions to said second torsion and cantilever positions to release the spring urging on the brush and permit the removal thereof.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view of a brush holderassembly incorporating the invention; and

FIG. 2 is a plan view of the assembly of the FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing shows a brush holder assembly 11 which includes generally a body 12, a brush 13, a spring 14 and a brush finger 15. The body '12 has fastening bolts 17 to fasten this body to the frame of a dynamoelectric machine 18. These fastening bolts 17 may provide the usual adjustment in two different planes to provide proper positioning of the brush inboard end 19 relative to a commutator or slip ring 20. The electrical current may pass directly from an electrically conductive brush holder body 12 to the brush 13 or may pass primarily through a flexible pigtail lead 22, depending upon the construction of the machine 18.

The brush,13 is prismatic and is shown as being a rectangular solid, except for the arcuate commutator contacting face, and this brush 13 fits within a complementarily shaped aperture 23 in the body 12. v

A fork is formed from walls 25 and 26 extending to one side of the aperture 23 and an axle 27 is fixed between these two walls. The combined torsion and cantilever spring 14 has a coil 28 wound around this axle 27 and has first and second ends 29 and 30. The first end 29 extends generally tangentially and abuts a bottom wall 31 which is a part of the body 12 and which extends between the two fork walls 25 and 26. The second end 30 of the spring 14 has first, second and third portions, 32, 33 and 34, respectively, and disposed in that order. The first portion 32 extends generally tangentially from the spring coil 28. The second portion 33 extends generally at right angles to both the first and third portions, This second portion 33, extends generally parallel to the axis 35 of the axle 27. The third portion 34, because of its extending generally at right angles to the second portion 33, again extends generally radially from the spring coil 28 and is bent into a loop in order to form a convenient manual handle 36. The outer radial edge of the fork wall 26 has a cam wall 39 which may be considered a disc cam or radial cam which terminates in a detent notch 40. The second portion 33 of the second end 30 of the spring 14 cooperates with this cam wall 39 and with the detent notch as a detent means. In so cooperating with the cam wall 39 and detent notch 40, this spring 14 is stressed as a cantilever spring and deflects this second portion 33 from its normal unstressed position which would be closely adjacent the spring coil 28.

The brush finger 15 is a flat metallic finger having fork walls 42 and 43 which straddle the ends of the spring coil 28 and have apertures journaled on the axle 27. This brush finger 15 has a forward extension 45 acting on the outboard end 46 of the brush l3 and has a rearward extension 47 overlying and coacting with the second portion 33 of the second end 30 of the spring 14.

The solid lines of FIGS. 1 and 2 show the brush holder assembly l 1 in position wherein the spring 14 is stressed as a torsion spring and acts through the brush finger 15 to urge the brush 13 toward engagement with the commutator or slip ring 20. It performs this urging by the first end 29 of the spring acting against the body 12 and the second end 30 of the spring 14 acting on the underside of the rearward extension 47 of the brush fingerlS. Because this brush finger 15 is pivoted at the axle 27 on the body 12, the forward extension 45 has a downward component of force acting on the brush 13.

When the brush 13 has worn away and requires replacement, then an operator may grasp the handle 36 and push it downwardly to the dotted line position 36A shown in FIG. 1. In so doing, this will slide the second portion 33 of the second end 30 of the spring 14 along the cam wall 39 until this second portion 33 drops into the detent notch 40. At this position the spring will be in a second torsion and cantilever position compared to the first torsion and cantilever position in which it is shown in solid lines in FlG. l. The spring 14 will be retained in this second position by the detent notch 40. In these second positions the spring 14 is stressed even further as a torsion spring because the coil 28 has been wrapped tighter around the axle 27. The spring 14 may or may not be stressed more as a cantilever spring in this second position compared to the first position, depending upon the change in radius along the cam wall 39 between the first and second cantilever positions. It is not necessary that the second portion 33 even contact the cam wall 39 when the handle is in the first position or solid line position shown in FIG. 1; it is only necessary that this second portion 33 be stressed as a cantilever spring when in engagement with the detent notch 40.

When the spring 14 is in the second torsion and cantilever positions shown as the dotted line positions of FIG. 1, then it will be observed that the rearward extension 47 on the brush finger 15 may be depressed freely so that the brush finger l5 lies in the dotted line position A of FIG. 1. Alternatively in order to reach this position the rearward extension 47 of the brush finger 15 may be depressed to directly act on the second portion 33 of the spring 14 to move it to the second torsion and cantilever positions. In such second position of the spring 14 and the brush finger 15, it will be observed that the forward extension 45 of the brush finger is removed from the outboard end 46 of the brush 13.-Accordingly the operator may now with the same hand and by the use of only one such hand, easily remove the brush 13 from the body 12. This may be accomplished by gently pulling on the flexible lead 22. Next a new brush may be inserted and then it is merely necessary to grasp the handle 36 and pull radially away from the axle 27 whereu pon the second portion 33 of the spring 14 will be disengaged from the detent notch 40. This pulling radially away will increasingly stress the spring 14 as a cantilever spring and will permit release of the detent means so that the torsion stressing of this spring 14 will return the handle 36 and consequently the brush finger 15 to the first position, shown in solid lines in FIG. 1. The brush holder assembly 11 is now returned to its position of use.

It will be observed that only one hand is required to manipulate the manual handle 36 and the brush finger 15 as well as the replacement of the brush 13 and this is a definite advantage when the brush holder assembly 11 is mounted in a cramped space which is usually the case. It permits the operator to easily see what he is doing since he does not have to have two hands in this cramped space in order to change the brush 13. Also, by requiring use of only one hand, this considerably reduces the shock hazard in the event that electric potential has not been removed from the machine terminals. The brush holder assembly 11 is one which readily permits easy and simple manipulation of the spring 14, the finger l5, and the brush 13 and hence promotes safe working habits.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What I claim is:

l. A brush holder assembly comprising, in combination,

a body,

a brush movably carried on said body'for electrical engagement with a commutator or slip ring,

a combined torsion and cantilever spring having first and second ends, detent means cooperating between said spring and said body, 7

means mounting said spring for movement between first and second torsion spring positions with one of said positions acting between said body and said brush to urge said brush toward the commutator slip ring,

the other of said positions being an inactive position wherein said brush is not urged toward the commutator or slip ring,

and means mounting said spring for movement between first and second cantilever spring positions with one of said positions being at said detent means and stressed as a cantilever spring and the other of said positions being spaced from said detent means,

whereby an operator with one hand may move said spring from the first torsion and cantilever positions to said second torsion and cantilever positions to release the spring urging on the brush and permit the removal thereof.

2. A brush holder assembly as set forth in claim 1, wherein said first torsion spring position stresses said spring as a torsion spring to urge said brush toward the commutator or slip ring.

3. A brush holder assembly as set forth in claim 1, wherein said second cantilever spring position is with said spring at said detent means and stressed as a cantilever spring,

said cantilever spring stressing causing retention of said spring in said detent means.

4. A brush holder assembly as set forth in claim 1, including a brush finger carried on said body and acting on said brush and having a portion acting on said spring.

5. A brush holder assembly as set forth in claim 1, including a brush finger pivoted on said body and having a rearward extension and having a forward extension cooperating with the outboard end of said brush.

6. A brush holder assembly as set forth in claim 5, wherein said spring acts on said rearward extension of said brush finger.

7. A brush holder assembly as set forth in claim 1, including a detent notch as said detent means and mounted on said body,

said first end of said spring acting on said body and said second end of said spring cooperating with said detent notch.

8. A brush holder assembly as set forth in claim 7, wherein said first end of said spring has first, second and third portions disposed in that order,

said second portion extending generally parallel to the axis of said spring,

said detent notch being a radial notch in said body to cooperate with said secondportion of said second end of said spring.

9. A brush holder assembly as set forth in claim 8, wherein said second portion of said spring extends generally at right angles to both said first and third portions,

said spring being wound into a torsion coil to act as a torsion spring,

said first portion extending tangentially from said coil of said spring.

10. A brush holder assembly as set forth in claim 9, including a manual handle on said third portion of said second end of said spring.

11. A brush holder assembly as set forth in claim 1, including wall means in said body defining a brush aperture,

and means mounting said brush in said aperture for sliding movements.

12. A brush holder assembly as set forth in claim 11, including a fork extending to one side of said brush aperture on said body,

an axle extended across said fork,

and said spring being wound as a torsion coil around said axle.

' 13. A brush holder assembly as set forth in claim 12, including a detent notch in one side of said fork as part of said detent means.

14. A brush holder assembly as set forth in claim 13, wherein said detent notch is a radially extending notch,

and -a cam wall adjacent said detent notch to increasingly stress said spring second end as a cantilever spring upon movement of said spring from said first to said second cantilever positions,

whereby said spring must be stressed further as a cantilever spring to release said second end of said spring from said detent notch in order to return the spring second end from said second torsion and cantilever positions to said first torsion and cantilever positions to effect spring urging on the brush. 

1. A brush holder assembly comprising, in combination, a body, a brush movably carried on said body for electrical engagement with a commutator or slip ring, a combined torsion and cantilever spring having first and second ends, detent means cooperating between said spring and said body, means mounting said spring for movement between first and second torsion spring positions with one of said positions acting between said body and said brush to urge said brush toward the commutator slip ring, the other of said positions being an inactive position wherein said brush is not urged toward the commutator or slip ring, and means mounting said spring for movement between first and second cantilever spring positions with one of said positions being at said detent means and stressed as a cantilever spring and the other of said positions being spaced from said detent means, whereby an operator with one hand may move said spring from the first torsion and cantilever positions to said second torsion and cantilever positions to release the spring urging on the brush and permit the removal thereof.
 2. A brush holder assembly as set forth in claim 1, wherein said first torsion spring position stresses said spring as a torsion spring to urge said brush toward the commutator or slip ring.
 3. A brush holder assembly as set forth in claim 1, wherein said second cantilever spring position is with said spring at said detent means and stressed as a cantilever spring, said cantilever spring stressing causing retention of said spring in said detent means.
 4. A brush holder assembly as set forth in claim 1, including a brush finger carried on said body and acting on said brush and having a portion acting on said spring.
 5. A brush holder assembly as set forth in claim 1, including a brush finger pivoted on said body and having a rearward extension and having a forward extension cooperating with the outboard end of said brush.
 6. A brush holder assembly as set forth in claim 5, wherein said spring acts on said rearward extension of said brush finger.
 7. A brush holder assembly as set forth in claim 1, including a detent notch as said detent means and mounted on said body, said first end of said spring acting on said body and said second end of said spring cooperating with said detent notch.
 8. A brush holder assembly as set forth in claim 7, wherein said first end of said spring has first, second and third portions disposed in that order, said second portion extending generally parallel to the axis of said spring, said detent notch being a radial notch in said body to cooperate with said second portion of said second end of said spring.
 9. A brush holder assembly as set forth in claim 8, wherein said second portion of said spring extends generally at right angles to both said first and third portions, said spring being wound into a torsion coil to act as a torsion spring, said first portion extending tangentially from said coil of said spring.
 10. A brush holder assembly as set forth in claim 9, including a manual handle on said third portion of said second end of said spring.
 11. A brush holder assembly as set forth in claim 1, including wall means in said body defining a brush aperture, and means mounting said brush in said aperture for sliding movements.
 12. A brush holder assembly as set forth in claim 11, including a fork extending to one side of said brush aperture on said body, an axle extended across said fork, and said spring being wound as a torsion coil around said axle.
 13. A brush holder assembly as set forth in claim 12, including a detent notch in one side of said fork as part of said detent means.
 14. A brush holder assembly as set forth in claim 13, wherein said detent notch is a radially extending notch, and a cam wall adjacent said detent notch to increasingly stress said spring second end as a cantilever spring upon movement of said spring from said first to said second cantilever positions, whereby said spring must be stressed further as a cantilever spring to release said second end of said spring from said detent notch in order to return the spring second end from said second torsion and cantilever positions to said first torsion and cantilever positions to effect spring urging on the brush. 